/*
 * Copyright (c) 2000-2010 Marc Alexander Lehmann <schmorp@schmorp.de>
 *
 * Redistribution and use in source and binary forms, with or without modifica-
 * tion, are permitted provided that the following conditions are met:
 *
 *   1.  Redistributions of source code must retain the above copyright notice,
 *       this list of conditions and the following disclaimer.
 *
 *   2.  Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *
 * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR IMPLIED
 * WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MER-
 * CHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO
 * EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPE-
 * CIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,
 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS;
 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY,
 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTH-
 * ERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED
 * OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * Alternatively, the contents of this file may be used under the terms of
 * the GNU General Public License ("GPL") version 2 or any later version,
 * in which case the provisions of the GPL are applicable instead of
 * the above. If you wish to allow the use of your version of this file
 * only under the terms of the GPL and not to allow others to use your
 * version of this file under the BSD license, indicate your decision
 * by deleting the provisions above and replace them with the notice
 * and other provisions required by the GPL. If you do not delete the
 * provisions above, a recipient may use your version of this file under
 * either the BSD or the GPL.
 */

#include "../lib/lzfP.h"

#if AVOID_ERRNO
#define SET_ERRNO(n)
#else
#include <errno.h>
#define SET_ERRNO(n) errno = (n)
#endif

#if USE_REP_MOVSB /* small win on amd, big loss on intel */
#if (__i386 || __amd64) && __GNUC__ >= 3
#define lzf_movsb(dst, src, len)                \
   asm ("rep movsb"                              \
        : "=D" (dst), "=S" (src), "=c" (len)     \
        :  "0" (dst),  "1" (src),  "2" (len));
#endif
#endif

unsigned int
lzf_decompress ( const void *const in_data, unsigned int in_len,
                 void *out_data, unsigned int out_len )
{
    u8 const *ip = ( const u8 * ) in_data;
    u8 *op = ( u8 * ) out_data;
    u8 const *const in_end = ip + in_len;
    u8 * const out_end = op + out_len;

    do
    {
        unsigned int ctrl = * ip ++;

        if ( ctrl < ( 1 << 5 ) ) /* literal run */
        {
            ctrl ++;

            if ( op + ctrl > out_end )
            {
                SET_ERRNO (E2BIG);
                return 0;
            }

#if CHECK_INPUT
            if ( ip + ctrl > in_end )
            {
                SET_ERRNO (EINVAL);
                return 0;
            }
#endif

#ifdef lzf_movsb
            lzf_movsb (op, ip, ctrl);
#else
            switch ( ctrl )
            {
                case 32: *op ++ = * ip ++;
                    case 31: *op ++ = * ip ++;
                    case 30: *op ++ = * ip ++;
                    case 29: *op ++ = * ip ++;
                case 28: *op ++ = * ip ++;
                    case 27: *op ++ = * ip ++;
                    case 26: *op ++ = * ip ++;
                    case 25: *op ++ = * ip ++;
                case 24: *op ++ = * ip ++;
                    case 23: *op ++ = * ip ++;
                    case 22: *op ++ = * ip ++;
                    case 21: *op ++ = * ip ++;
                case 20: *op ++ = * ip ++;
                    case 19: *op ++ = * ip ++;
                    case 18: *op ++ = * ip ++;
                    case 17: *op ++ = * ip ++;
                case 16: *op ++ = * ip ++;
                    case 15: *op ++ = * ip ++;
                    case 14: *op ++ = * ip ++;
                    case 13: *op ++ = * ip ++;
                case 12: *op ++ = * ip ++;
                    case 11: *op ++ = * ip ++;
                    case 10: *op ++ = * ip ++;
                    case 9: *op ++ = * ip ++;
                case 8: *op ++ = * ip ++;
                    case 7: *op ++ = * ip ++;
                    case 6: *op ++ = * ip ++;
                    case 5: *op ++ = * ip ++;
                case 4: *op ++ = * ip ++;
                    case 3: *op ++ = * ip ++;
                    case 2: *op ++ = * ip ++;
                    case 1: *op ++ = * ip ++;
            }
#endif
        }
        else /* back reference */
        {
            unsigned int len = ctrl >> 5;

            u8 *ref = op - ( ( ctrl & 0x1f ) << 8 ) - 1;

#if CHECK_INPUT
            if ( ip >= in_end )
            {
                SET_ERRNO (EINVAL);
                return 0;
            }
#endif
            if ( len == 7 )
            {
                len += * ip ++;
#if CHECK_INPUT
                if ( ip >= in_end )
                {
                    SET_ERRNO (EINVAL);
                    return 0;
                }
#endif
            }

            ref -= * ip ++;

            if ( op + len + 2 > out_end )
            {
                SET_ERRNO (E2BIG);
                return 0;
            }

            if ( ref < ( u8 * ) out_data )
            {
                SET_ERRNO (EINVAL);
                return 0;
            }

#ifdef lzf_movsb
            len += 2;
            lzf_movsb (op, ref, len);
#else
            switch ( len )
            {
                default:
                    len += 2;

                    if ( op >= ref + len )
                    {
                        /* disjunct areas */
                        memcpy (op, ref, len);
                        op += len;
                    }
                    else
                    {
                        /* overlapping, use octte by octte copying */
                        do
                            *op ++ = * ref ++;
                        while ( -- len );
                    }

                    break;

                case 9: *op ++ = * ref ++;
                case 8: *op ++ = * ref ++;
                case 7: *op ++ = * ref ++;
                case 6: *op ++ = * ref ++;
                case 5: *op ++ = * ref ++;
                case 4: *op ++ = * ref ++;
                case 3: *op ++ = * ref ++;
                case 2: *op ++ = * ref ++;
                case 1: *op ++ = * ref ++;
                case 0: *op ++ = * ref ++; /* two octets more */
                    *op ++ = * ref ++;
            }
#endif
        }
    }
    while ( ip < in_end );

    return op - ( u8 * ) out_data;
}

